The primary purpose of the proposed research is to extend the longitudinal behavioral genetic study of aging known as SATSA (the Swedish Adoption/Twin Study of Aging) with a longitudinal follow-up 16 years after the initial in-person testing of 485 individuals from approximately 350 twin pairs, allowing for up to 5 times of in-person testing per subject. In addition, the study will obtain a fifth wave of self-report data on the 1471 individuals who have ever participated in any form of SATSA assessment and are still living. The point at which any participant shows onset of cognitive impairment or dementia as well as mortality information will be linked to the dataset. Of principal interest are analyses of genetic and environmental contributions to individual differences in long-term change and continuity late in life with respect to measures of cognition and health, including health related behavior. Analyses within domains will focus on the trajectory of change with age, investigation of whether age changes differ by cohort, and identifying the most informative predictors of survival. Analyses between domains will investigate the nature of the relationships between cognitive and health variables, as well as examining the direction of effect and the genetic and environmental contributions to the observed relationships. Specific hypotheses about the nature of these relationships will be tested. With an expanded number of measurement occasions as well as the cohort sequential design of the study, we will have an unprecedented opportunity to evaluate issues concerning patterns of aging, including turning points after which decline accelerates, how patterns of decline are related to mortality (terminal decline), which changes precede others, and what factors appear to precipitate or to protect against decline. The explication of individual differences in aging has basic research implications for increased understanding of the fundamental processes of normal and pathological aging, as well as applied implications for treating disorders, preventing disease, and optimizing quality of life.